1. Field of the Invention
This invention relates to magnetic recording disk files and relates more particularly to methods for overcoming forces tending to bind the magnetic sliders and heads to the disk surfaces when the disk or disks have been at rest.
2. Description of Prior Art
In current magnetic recording disk files there have been problems encountered with the sliders containing magnetic heads tending to adhere to the surface of the disk or disks after the disk has been at rest. This adhering or stiction problem is aggravated by the presence on the disk surface of lubricant material which studies have shown tends to puddle up between the disk surface and the slider when the disk is not in motion and the slider rests on the disk surface. This stiction problem is a relatively new one in magnetic disk files. In early magnetic disk files, as exemplified by the IBM 2311, 2314 and 3330 disk drives, the magnetic sliders were never in contact with the magnetic record surface (except in the event of an inadvertent head "crash"). Instead, the sliders were removed from the disk area prior to powering down the disk drive and, upon powering up, were not repositioned over the disk area until the disks were rotating at a speed sufficient to generate an air-bearing for supporting the sliders in a "flying" mode above the rotating disk surface. Hence, disk files of this type had no "stiction" problems between the slider and disk.
With the advent of the IBM 3340 disk drive in 1973, the "start-stop in-contact" mode of the disk file operation was introduced with a lubricant applied to the disk surface. This disk file and subsequent files permitted the sliders to contact the recording disk surface (usually in a non-data portion thereof) when the file was powered down, and were in contact with the surfaces when the file was powered up. It is in this latter situation that possible problems with stiction arise.
In the disk files involved herein, the sliders are movable radially of the disk to be positioned over a selected one of a group of concentric recording tracks. The sliders are carried on a suspension assembly connected ultimately to an actuator. The slider and its suspension have relatively good rigidity radially of the disk, but they are somewhat fragile when subjected to tangential force. Such tangential force is just what is applied to the suspension when stiction is encountered. As the disk begins rotation, the lubricant under the slider face tends to hold the slider, and as the disk picks up rotational speed, substantial forces can be applied tangentially of the slider and suspension, resulting in damage to or destruction of the suspension, and possible damage to the disk surface.